Polymer Compositions Comprising Alkyl Silicone and Articles Formed from Same

This application is a continuation application that claims the benefit of priority to International Application No. PCT/US2025/020150, filed Mar. 17, 2025, which claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Ser. No. 63/566,611 filed on Mar. 18, 2024, U.S. Provisional Application Ser. No. 63/710,186 filed on Oct. 22, 2024, U.S. Provisional Application Ser. No. 63/769,712 filed on Mar. 10, 2025, U.S. Provisional Application Ser. No. 63/650,679 filed on May 22, 2024, U.S. Provisional Application Ser. No. 63/769,721 filed on Mar. 10, 2025, and U.S. Provisional Application Ser. No. 63/702,451 filed on Oct. 2, 2024, the contents of each of which are relied upon and are incorporated herein by reference in their entireties.

The present specification generally relates to polymer compositions and, in particular, to polymer compositions comprising an alkyl silicone that form articles having low fluid retention and/or low binding to biological matter.

Polymeric parts having low fluid retention surfaces may have various applications, such as pipette tips, cell culture ware, assay plates, and liquid handling vessels, among other examples. Conventionally, fluorinated compounds may be added to polymer compositions to reduce fluid retention. However, the use of fluorinated compounds may lead to increased manufacturing times, due to slow surface development of the fluorinated compound. Moreover, the use of fluorinated compounds in polymeric parts is believed to have a negative impact on the environment. Further, polymeric parts having fluorinated compounds in their composition may bind to material of biological origin, decreasing the recovery percentage of biological-based products, which is undesirable.

Therefore, a continuing need exists for polymer compositions for use in forming articles, but that have reduced fluid retention and/or low binding with materials of biological origin.

It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

Reference will now be made in detail to various embodiments of polymer compositions and articles formed from the polymer compositions and having low fluid retention.

According to embodiments, the polymer compositions include an alkyl silicone and a thermoplastic polymer. The alkyl silicone may have a specified molecular weight (e.g., greater than or equal to 1,000 g/mol and less than or equal to 10,000 g/mol) and dimethyl silicone content (e.g. greater than or equal 40 wt. % and less than or equal to 70 wt. % dimethyl silicone, based on a total weight of the alkyl silicone), which results in an article having low fluid retention and low haze.

According to embodiments, a method for forming an article including a polymer composition may comprise solidifying the polymer composition within a mold to form an article and removing the article from the mold. The polymer composition may include an alkyl silicone and a thermoplastic polymer. The polymer composition may include greater than or equal to 0.5 wt. % and less than or equal to 20 wt. % alkyl silicone. The alkyl silicone may have a molecular weight greater than or equal to 1,000 g/mol and less than or equal to 10,000 g/mol. The alkyl silicone may have a dimethyl silicone content greater than or equal to 40 wt. % and less than or equal to 70 wt. %, based on a total weight of the alkyl silicone.

According to embodiments, a non-fluorinated article includes a polymer composition. The non-fluorinated article has a fluid retention of less than or equal to 11%. The non-fluorinated article is resistant to isopropanol, and the non-fluorinated article is free or substantially free of fluorine.

Ranges may be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

Directional terms as used herein-for example up, down, right, left, front, back, top, bottom-are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

As used herein, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.

The term “substantially free,” when used to describe the amount and/or absence of a particular component in a composition and the resultant article, means that the component is not intentionally added to the composition and the resultant article. However, the composition and the resultant article may contain traces of the component as a contaminant or tramp in amounts of less than 0.05 weight percent (wt. %).

The term “free,” when used to describe the amount and/or absence of a particular component in a composition and the resultant articles, means that the component is not present in the article.

As described herein, polymeric parts (articles) having low fluid retention surfaces and/or surfaces with low binding to biological matter may have various applications, such as pipette tips, centrifuge tubes, cell culture ware, assay plates, and liquid handling vessels, among other examples. As used herein, “biological matter” refers to matter produced by cells such as DNA, proteins, extra cellular matrices, among other examples. It may be desirable to avoid use of fluorinated compounds in polymer compositions to reduce fluid retention due to increased manufacturing times and their negative environmental impact.

Low molecular weight alkyl silicones, such as those with only methyl pendant groups, have also conventionally been used to produce low fluid retention surfaces. However, due to their relatively lower molecular weight, inclusion of such alkyl silicones in polymer compositions may result in an undesirable increase in fluid retention and haze. Moreover, low molecular weight alkyl silicones may be soluble in common reagents, such as isopropyl alcohol, leading to contamination of fluid that contacts the article made of the polymer composition.

Disclosed herein are polymer compositions and articles comprising same that mitigate the aforementioned problems. Specifically, the polymer compositions disclosed herein comprise an alkyl silicone comprising a specified molecular weight (e.g., greater than or equal to 1,000 g/mol and less than or equal to 10,000 g/mol) and silicone content (e.g., greater than or equal 40 wt. % and less than or equal to 70 wt. % silicone, based on a total weight of the alkyl silicone), which results in an article having low fluid retention (e.g., less than or equal to 10%). The specified molecular weight and silicone content of the alkyl silicones described herein ensure separation of the alkyl silicone from the polymer and migration towards the surface of the polymeric part or article being formed during manufacturing. The increased alkyl silicone content on or near the article (polymeric part) surface may result in the article having low fluid retention. The articles formed from the polymer compositions described herein are non-fluorinated articles having low fluid retention. As used herein, a “non-fluorinated article” is an article formed from a polymer composition that is free or substantially free of fluorine.

The polymer compositions described herein may be described as comprising alkyl silicone and a thermoplastic polymer.

The polymer composition may undergo surface development during manufacturing, such that alkyl silicone migrates to the surface of the article formed from the polymer composition. This may contribute to the lower fluid retention properties of articles formed from the polymer composition. However, if the molecular weight of the alkyl silicone is too great, for example greater than 10,000 g/mol, then the alkyl silicone may not migrate to the surface of an article formed from the polymer composition. Furthermore, if the molecular weight of the alkyl silicone is not great enough, for example less than 1,000 g/mol, then the alkyl silicone may be less resistant to certain solvents, such as isopropanol. Low solvent resistance may result in alkyl silicone being removed from the surface of the article, which may lead to contamination of samples. A relatively low or high molecular weight (e.g., less than 1,000 g/mol or greater than 10,000 g/mol) may lead to an increase in haze, which may be undesirable in certain applications.

According to embodiments, the alkyl silicone may have a molecular weight greater than or equal to 1,000 g/mol and less than or equal to 10,000 g/mol. As used herein, “molecular weight” refers to weight average molecular weight. For example, without limitation, the alkyl silicone may have a molecular weight greater than or equal to 1,000 g/mol and less than or equal to 10,000 g/mol, greater than or equal to 2,000 g/mol and less than or equal to 10,000 g/mol, greater than or equal to 3,000 g/mol and less than or equal to 10,000 g/mol, greater than or equal to 4,000 g/mol and less than or equal to 10,000 g/mol, greater than or equal to 5,000 g/mol and less than or equal to 10,000 g/mol, greater than or equal to 6,000 g/mol and less than or equal to 10,000 g/mol, greater than or equal to 7,000 g/mol and less than or equal to 10,000 g/mol, greater than or equal to 8,000 g/mol and less than or equal to 10,000 g/mol, greater than or equal to 9,000 g/mol and less than or equal to 10,000 g/mol, greater than or equal to 1,000 g/mol and less than or equal to 9,000 g/mol, greater than or equal to 1,000 g/mol and less than or equal to 8,000 g/mol, greater than or equal to 1,000 g/mol and less than or equal to 7,000 g/mol, greater than or equal to 1,000 g/mol and less than or equal to 6,000 g/mol, greater than or equal to 1,000 g/mol and less than or equal to 5,000 g/mol, greater than or equal to 1,000 g/mol and less than or equal to 4,000 g/mol, greater than or equal to 1,000 g/mol and less than or equal to 3,000 g/mol, greater than or equal to 1,000 g/mol and less than or equal to 2,000 g/mol, or any range or combination of ranges formed from these endpoints. In some embodiments, the alkyl silicone may have a molecular weight from 1,500 g/mol to 8,000 g/mol.

According to embodiments described herein, an “alkyl silicone” is a polymer comprising repeating units of siloxane, where at least some of the siloxane monomers are functionalized with alkyl groups other than methyl groups. In one or more embodiments, some of the siloxane monomers may comprise dimethyl siloxane. The content of dimethyl siloxane monomers in an alkyl silicone may be referred to as the “dimethyl silicone content” of the alkyl silicone. If the dimethyl silicone content of the alkyl silicone is too low (e.g., less than 40 wt. %), then the alkyl silicone may have difficulty moving to the surface of an article formed from the polymer composition during manufacturing. This may increase manufacturing times and lead to poor fluid retention properties of articles comprising the polymer composition. If the dimethyl silicone content of the alkyl silicone is too great, for example greater than 70 wt. %, then articles formed from the polymer composition may similarly have poor surface development. A relatively high dimethyl silicone content may also increase haze, which may be undesirable in certain applications.

In embodiments, the alkyl silicone may have a dimethyl silicone content of greater than or equal to 40 wt. % and less than or equal to 70 wt. % based on a total weight of the alkyl silicone. For example, the alkyl silicone may have a dimethyl silicone content, based on the total weight of the alkyl silicone, greater than or equal to 40 wt. % and less than or equal to 70 wt. %, greater than or equal to 45 wt. % and less than or equal to 70 wt. %, greater than or equal to 50 wt. % and less than or equal to 70 wt. %, greater than or equal to 55 wt. % and less than or equal to 70 wt. %, greater than or equal to 60 wt. % and less than or equal to 70 wt. %, greater than or equal to 65 wt. % and less than or equal to 70 wt. %, greater than or equal to 40 wt. % and less than or equal to 65 wt. %, greater than or equal to 40 wt. % and less than or equal to 60 wt. %, greater than or equal to 40 wt. % and less than or equal to 55 wt. %, greater than or equal to 40 wt. % and less than or equal to 50 wt. %, greater than or equal to 40 wt. % and less than or equal to 45 wt. %, or any range or combination of ranges formed from these endpoints. In some embodiments, a dimethyl silicone content of the alkyl silicone may be greater than or equal to 45 wt. % and less than or equal to 65 wt. %.

The carbon content of the alkyl groups may affect the compatibility of the alkyl silicone with the thermoplastic polymer used in the polymer composition. If the number of carbon atoms in the alkyl groups of the alkyl silicone is too great, for example greater than 45 carbon atoms, then the alkyl silicone may be too compatible with the thermoplastic polymer and may not migrate to the surface of the formed part. Additionally, the number of carbon atoms in the alkyl groups of the alkyl silicone may contribute to the solvent resistance of articles formed from the polymer composition. If the number of carbon atoms in the alkyl groups is too small, for example less than 8 carbon atoms, then articles formed from the polymer composition may not exhibit sufficient solvent resistance.

In one or more embodiments, the alkyl silicone may comprise C-Calkyl groups. As described herein, a “Calkyl group” refers to an alkyl group comprising X number of carbon atoms. For example, a Ccarbon group comprisescarbon atoms. In embodiments, the alkyl silicone may comprise C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, C-Calkyl groups, or alkyl groups having a range of the number of carbon atoms formed from any of these endpoints. In some embodiments, the alkyl silicone may comprise C-Calkyl groups.

The carbon content of the alkyl groups of the alkyl silicone may correlate to a melting point of the alkyl silicone, with a relatively higher carbon content corresponding to a relatively higher melting point. As such, a melting point of the alkyl silicone may contribute to compatibility and solvent resistance, similar to the carbon content of the alkyl groups. According to embodiments described herein, the alkyl silicone may comprise a melting point greater than or equal to 25° C. and less than or equal to 100° C. For example, without limitation, the alkyl silicone may have a melting point greater than or equal to 25° C. and less than or equal to 100° C., greater than or equal to 35° C. and less than or equal to 100° C., greater than or equal to 45° C. and less than or equal to 100° C., greater than or equal to 55° C. and less than or equal to 100° C., greater than or equal to 65° C. and less than or equal to 100° C., greater than or equal to 75° C. and less than or equal to 100° C., greater than or equal to 85° C. and less than or equal to 100° C., greater than or equal to 95° C. and less than or equal to 100° C., greater than or equal to 25° C. and less than or equal to 90° C., greater than or equal to 25° C. and less than or equal to 80° C., greater than or equal to 25° C. and less than or equal to 70° C., greater than or equal to 25° C. and less than or equal to 60° C., greater than or equal to 25° C. and less than or equal to 50° C., greater than or equal to 25° C. and less than or equal to 40°° C., greater than or equal to 25° C. and less than or equal to 30° C., or any range or combination of ranges formed from these endpoints. In some embodiments, the alkyl silicone may comprise a melting point greater than or equal to 30° C. and less than or equal to 65° C.

If the amount of alkyl silicone in the polymer composition is too low, for example less than 0.5 wt. %, then articles formed from the polymer composition may not exhibit the desired low fluid retention properties. Additionally, minimizing the amount of alkyl silicone, such as in amounts less than or equal to 20 wt. %, may be cost effective.

Embodiments of the polymer compositions described herein may comprise, based on a total weight of the polymer composition, greater than or equal to 0.5 wt. % and less than or equal to 20 wt. % alkyl silicone. For example, without limitation, the polymer compositions may comprise alkyl silicone in an amount, based on the total weight of the polymer composition, greater than or equal to 0.5 wt. % and less than or equal to 20 wt. %, greater than or equal to 1 wt. % and less than or equal to 20 wt. %, greater than or equal to 3 wt. % and less than or equal to 20 wt. %, greater than or equal to 5 wt. % and less than or equal to 20 wt. %, greater than or equal to 7 wt. % and less than or equal to 20 wt. %, greater than or equal to 9 wt. % and less than or equal to 20 wt. %, greater than or equal to 11 wt. % and less than or equal to 20 wt. %, greater than or equal to 13 wt. % and less than or equal to 20 wt. %, greater than or equal to 15 wt. % and less than or equal to 20 wt. %, greater than or equal to 17 wt. % and less than or equal to 20 wt. %, greater than or equal to 19 wt. % and less than or equal to 20 wt. %, greater than or equal to 0.5 wt. % and less than or equal to 18 wt. %, greater than or equal to 0.5 wt. % and less than or equal to 16 wt. %, greater than or equal to 0.5 wt. % and less than or equal to 14 wt. %, greater than or equal to 0.5 wt. % and less than or equal to 12 wt. %, greater than or equal to 0.5 wt. % and less than or equal to 10 wt. %, greater than or equal to 0.5 wt. % and less than or equal to 8 wt. %, greater than or equal to 0.5 wt. % and less than or equal to 6 wt. %, greater than or equal to 0.5 wt. % and less than or equal to 4 wt. %, greater than or equal to 0.5 wt. % and less than or equal to 2 wt. %, greater than or equal to 0.5 wt. % and less than or equal to 1 wt. %, or any range or combination of ranges formed from these endpoints. In some embodiments, the polymer composition may comprise greater than or equal to 1 wt. % and less than or equal to 15 wt. % alkyl silicone.

In one or more embodiments, the polymer composition may comprise an alkyl containing molecule. As described herein, “alkyl containing molecules” include one or more alkyl groups and a molecular segment that reduces compatibility of the alkyl containing molecule with the thermoplastic polymer. In one or more embodiments, the alkyl containing molecules are alkyl silicones. It should be understood that references to alkyl silicones throughout the description may also be considered to generally refer to “alkyl containing molecules.” For example, the polymer composition may comprise greater than or equal to 0.5 wt. % and less than or equal to 20 wt. % of an alkyl containing molecule, based on the total weight of the polymer composition, as described hereinabove with respect to alkyl silicone. Additionally, properties of the alkyl containing molecules may be the same as properties of the alkyl silicones described hereinabove, including the molecular weight, alkyl chain length, and melting point. In some embodiments, the polymer composition may comprise an alkyl containing molecule in place of the alkyl silicone described hereinabove. Without intending to be bound by theory, the molecular segment that reduces compatibility of the alkyl containing molecule with the thermoplastic polymer in which the alkyl containing molecule is blended may aid in migration of the alkyl containing molecules to the surface of an article formed from the polymer composition comprising the alkyl containing molecule and the thermoplastic polymer. For example, alkyl silicones utilize silicone as the compatibility reducing molecular segment that brings the alkyl containing molecule to the surface. The compatibility reducing molecular segment may vary according to the thermoplastic polymer included in the polymer composition such that the compatibility reducing molecular segment is incompatible with the thermoplastic polymer. For example, the silicone of alkyl silicone molecules may be incompatible with a broad range of thermoplastic polymers including, but not limited to polypropylene. However, the compatibility reducing molecular segment is not necessarily limited to silicone.

The thermoplastic polymer included in the polymer compositions described herein is not necessarily limited. For example, the thermoplastic polymer may be selected based on the intended use of the article formed from the polymer composition. In embodiments, the thermoplastic polymer comprises polypropylene, polystyrene, polymethylmethacrylate, polyvinyl chloride, polycarbonate, polysulfone, polyester, polyamide, polystyrene butadiene copolymers, fully hydrogenated styrenic polymers, polyurethanes, polyethylene, polymethyl pentene, polylactic acid, polybutylene succinate, polyhydroxyalkanoate, or a combination thereof. In some embodiments, the thermoplastic polymer may comprise a propylene homopolymer or a propylene ethylene copolymer. In some embodiments, the thermoplastic polymer may comprise polypropylene.

In some embodiments, the thermoplastic polymer may have a melt flow rate greater than or equal to 1 g/10 min. and less than or equal to 100 g/10 min. For example, the thermoplastic polymer may have a melt flow rate greater than or equal to 1 g/10 min. and less than or equal to 100 g/10 min., greater than or equal to 10 g/10 min. and less than or equal to 100 g/10 min., greater than or equal to 20 g/10 min. and less than or equal to 100 g/10 min., greater than or equal to 30 g/10 min. and less than or equal to 100 g/10 min., greater than or equal to 40 g/10 min. and less than or equal to 100 g/10 min., greater than or equal to 50 g/10 min. and less than or equal to 100 g/10 min., greater than or equal to 60 g/10 min. and less than or equal to 100 g/10 min., greater than or equal to 70 g/10 min. and less than or equal to 100 g/10 min., greater than or equal to 80 g/10 min. and less than or equal to 100 g/10 min., greater than or equal to 90 g/10 min. and less than or equal to 100 g/10 min., greater than or equal to 1 g/10 min. and less than or equal to 90 g/10 min., greater than or equal to 1 g/10 min. and less than or equal to 80 g/10 min., greater than or equal to 1 g/10 min. and less than or equal to 70 g/10 min., greater than or equal to 1 g/10 min. and less than or equal to 60 g/10 min., greater than or equal to 1 g/10 min. and less than or equal to 50 g/10 min., greater than or equal to 1 g/10 min. and less than or equal to 40 g/10 min., greater than or equal to 1 g/10 min. and less than or equal to 30 g/10 min., greater than or equal to 1 g/10 min. and less than or equal to 20 g/10 min., greater than or equal to 1 g/10 min. and less than or equal to 10 g/10 min., or any range or combination of ranges formed from these endpoints. As described herein, “melt flow rate” may be measured according to ASTM D1238. Without intending to be bound by theory, polymers having melt flow rates greater than or equal to 1 g/10 min. and less than or equal to 100 g/10 min. may relatively easily fill parts having thin walls and long flow paths while maintaining desirable physical properties.

In embodiments, the polymer composition may comprise, based on the total weight of the polymer composition, greater than or equal to 75 wt. % and less than or equal to 99.5 wt. %

of the thermoplastic polymer. For example, without limitation, the polymer composition may comprise thermoplastic polymer in an amount, based on the total weight of the polymer composition, greater than or equal to 75 wt. % and less than or equal to 99.5 wt. %, greater than or equal to 80 wt. % and less than or equal to 99.5 wt. %, greater than or equal to 85 wt. % and less than or equal to 99.5 wt. %, greater than or equal to 90 wt. % and less than or equal to 99.5 wt. %, greater than or equal to 95 wt. % and less than or equal to 99.5 wt. %, greater than or equal to 75 wt. % and less than or equal to 95 wt. %, greater than or equal to 75 wt. % and less than or equal to 90 wt. %, greater than or equal to 75 wt. % and less than or equal to 85 wt. %, greater than or equal to 75 wt. % and less than or equal to 80 wt. %, or any range or combination of ranges formed from these endpoints.

In some embodiments, the polymer composition may further comprise an additional polymer included as a dispersing agent, for example, when the polymer composition is processed in equipment that may not disperse the polymer composition well. For example, in embodiments, the additional polymer may comprise a polymer with a melting temperature and viscosity lower than that of the main polymer being utilized to mold the part being manufactured. The polymer may have a lower molecular weight than the main polymer to reduce the melt viscosity and may be a copolymer to allow for compatibility with the main resin while reducing the melting temperature. For example, for a polypropylene part, the polymer may be a random copolymer of propylene and ethylene. For a polystyrene part, the polymer may be a copolymer of styrene and butadiene which may or may not be hydrogenated. In embodiments, the polymer composition may comprise, based on the total weight of the polymer composition, greater than or equal to 0 wt. % and less than or equal to 12 wt. % of the additional polymer. For example, without limitation, the polymer composition may comprise the additional polymer in an amount, based on the total weight of the polymer composition, greater than or equal to 0 wt. % and less than or equal to 12 wt. %, greater than or equal to 0 wt. % and less than or equal to 10 wt. %, greater than or equal to 0 wt. % and less than or equal to 7 wt. %, greater than or equal to 0 wt. % and less than or equal to 5 wt. %, greater than or equal to 1 wt. % and less than or equal to 12 wt. %, greater than or equal to 1 wt. % and less than or equal to 10 wt. %, greater than or equal to 1 wt. % and less than or equal to 7 wt. %, greater than or equal to 1 wt. % and less than or equal to 5 wt. %, greater than or equal to 2 wt. % and less than or equal to 12 wt. %, greater than or equal to 2 wt. % and less than or equal to 10 wt. %, greater than or equal to 2 wt. % and less than or equal to 7 wt. %, greater than or equal to 2 wt. % and less than or equal to 5 wt. %, or any range or combination of ranges formed from these endpoints.

In some embodiments, the polymer composition may further comprise one or more additives. The additives that may be included in the polymer composition are not necessarily limited. In embodiments, the additives may comprise antioxidants, clarifying agents, nucleating agents, antistatic agents, colorants, radiation stability agents, and conductive agents. Antioxidants may be included in the polymer composition to prevent degradation of the polymers. Some embodiments of the polymer composition include multiple antioxidants. Clarifying agents and nucleating agents may improve the clarity of articles formed from the polymer composition. Without intending to be bound by theory, clarifying agents and nucleating agents may initiate the growth of crystalline phases of crystalline polymers, such as polypropylene. Increasing the number of relatively small crystalline structures in the article may reduce the light scattered by the crystalline phases improving the clarity of articles formed from the polymer composition. Antistatic agents may reduce the resistivity of the polymer composition to provide static protection. Colorants may be included in the polymer composition to impart color to articles formed form the polymer composition. Suitable colorants may be selected for use in transparent, translucent, or opaque articles. Radiation stability agents may be included in the polymer composition to reduce the effects of irradiation on the polymer composition. For example, radiation stability agents may reduce discoloration, such as yellowing, that may occur in some polymer compositions. Radiation stability agents may also reduce the effect of radiation on the mechanical properties of articles formed from the polymer composition. Conductive agents may be included in the polymer composition to improve the electrical conductivity of the polymer composition. Conductive agents may include, for example, carbon black and carbon fibers. Some conductive agents, such as carbon black, may also impart color to the polymer composition and articles formed from the polymer composition.

In embodiments where the polymer composition further comprises one or more additives, the polymer composition may comprise, based on the total weight of the polymer composition, greater than 0 wt. % and less than or equal to 5 wt. % of the one or more additives. For example, the polymer composition may comprise the one or more additives in an amount greater than 0 wt. % and less than or equal to 5 wt. %, greater than or equal to 0.5 wt. % and less than or equal to 5 wt. %, greater than or equal to 1 wt. % and less than or equal to 5 wt. %, greater than or equal to 1.5 wt. % and less than or equal to 5 wt. %, greater than or equal to 2 wt. % and less than or equal to 5 wt. %, greater than or equal to 2.5 wt. % and less than or equal to 5 wt. %, greater than or equal to 3 wt. % and less than or equal to 5 wt. %, greater than or equal to 3.5 wt. % and less than or equal to 5 wt. %, greater than or equal to 4 wt. % and less than or equal to 5 wt. %, greater than or equal to 4.5 wt. % and less than or equal to 5 wt. %, greater than 0 wt. % and less than or equal to 4.5 wt. %, greater than 0 wt. % and less than or equal to 4 wt. %, greater than 0 wt. % and less than or equal to 3.5 wt. %, greater than 0 wt. % and less than or equal to 3 wt. %, greater than 0 wt. % and less than or equal to 2.5 wt. %, greater than 0 wt. % and less than or equal to 2 wt. %, greater than 0 wt. % and less than or equal to 1.5 wt. %, greater than 0 wt. % and less than or equal to 1 wt. %, greater than 0 wt. % and less than or equal to 0.5 wt. %, or any range or combination of ranges formed from these endpoints. In embodiments, the polymer composition may be free or substantially free of additives.

In one or more embodiments, the polymer composition may be free or substantially free of fluorine. For example, the alkyl silicone may be free from any moieties or functionalities comprising fluorine. Likewise, the thermoplastic polymer may be free from any moieties or functionalities comprising fluorine. In embodiments where the polymer composition comprises one or more additives, the additives may each be free from fluorine. Without intending to be bound by theory, articles formed from polymer compositions that are free of fluorine may have reduced manufacturing times relative to articles formed from polymer compositions comprising fluorinated compounds. Furthermore, fluorinated compound in articles formed from polymer compositions that are used to handle biological samples may contaminate the biological samples. Using polymer compositions that are free from fluorine to form such articles may reduce the likelihood of such samples being contaminated. Additionally, in certain industries, it may be desirable to avoid fluorinated compounds due to their potential environmental impact.

Embodiments of the polymer compositions described herein may be used to form various articles. Such articles may comprise the polymer compositions previously described. In some embodiments, the articles may be formed from the polymer compositions. In some embodiments, the articles may consist essentially of the polymer composition.

The articles comprising the polymer composition are not necessarily limited. In one or more embodiments, the articles may comprise a pipette, pipette tip, an assay plate, a dish, plate, flask, or other vessel for cell culture, a liquid storage vessel, a tube, a liquid receptacle, or a laboratory consumable. As described herein, a “laboratory consumable” refer to any item for laboratory use that is replaced regularly after it is used or after it wears down. The article may be any article where low fluid retention is desirable. In some embodiments, the article comprises a pipette tip. As described hereinabove, articles formed from the polymer compositions may have low fluid retention and sufficient solvent resistance. These properties may be desirable for laboratory consumables, such as pipette tips.

Referring now to, an articlecomprising the polymer composition may comprise a first major surfaceand a second major surface. The second major surfacemay be opposite the first major surface. It should be noted that the shape of the article is not necessarily limited to the structure depicted in. Articles comprising the polymer composition may have any suitable form or shape. For example, the polymer composition may be shaped to form any of the articles described hereinabove.

In one or more embodiments, a concentration of the alkyl silicone at a depth from 0 nm to 10 nm from the first major surfaceof the articlemay be greater than a concentration of alkyl silicone at a midpointbetween the first major surfaceand the second major surfaceof the article. In such embodiments, the midpointbetween the first major surfaceand the second major surfaceis greater than 10 nm from the first major surface. In one or more embodiments, the concentration of the alkyl silicone at a depth from 0 nm to 10 nm from the first major surfaceof the articlemay be 2, 3, 5, 10, 15 or even 20 times greater than a concentration of alkyl silicone at a midpointbetween the first major surfaceand the second major surfaceof the article. Likewise, in one or more embodiments, the concentration of the alkyl silicone at a depth from 0 nm to 10 nm from the second major surfaceof the articlemay be greater than a concentration of the alkyl silicone at the midpointbetween the first major surfaceand the second major surfaceof the article. In such embodiments, the midpointbetween the first major surfaceand the second major surfaceis greater than 10 nm. In one or more embodiments, the concentration of the alkyl silicone at a depth from 0 nm to 10 nm from the second major surfaceof the articlemay be 2, 3, 5, 10, 15 or even 20 times greater than a concentration of alkyl silicone at a midpointbetween the second major surfaceand the second major surfaceof the article. The concentration of the alkyl silicone at a depth from 0 nm to 10 nm may be measured by x-ray photoelectron spectroscopy.

This difference in concentration of alkyl silicone between the surfaces of the article and the middle of the article may be achieved in several ways. For example, during manufacturing processes, alkyl silicone may separate from the thermoplastic polymer and migrate to the surface of the article formed from the polymer composition. In another example, the polymer composition may be formed within a mold for making an article, where the alkyl silicone coats the surface of the mold and the thermoplastic polymer is subsequently introduced to the mold. When the article is formed, the concentration of alkyl silicone may be greater on the surface of the article. Without intending to be bound by theory, increasing the concentration of alkyl silicone on the surface of an article may improve the fluid retention properties of the article; specifically, reducing the fluid retention of the article.

In one or more embodiments, the article may comprise a fluid retention of less than or equal to 11% of a volume of fluid aspirated (or otherwise added) in the article and then dispensed (or otherwise discarded), including at any value or in any range less than or equal to 11%. For example, the article may comprise a fluid retention of less than or equal to 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, or even 0%, of a volume aspirated (or otherwise added) in the article and then dispensed (or otherwise discarded). When the article is in the form of a pipette tip, the article may comprise a fluid retention of less than or equal or equal to 11% after a single aspirate/dispense cycle, including at any value between 11% and 0% or in any range between 11% and 0%. As described herein, “fluid retention” for a pipette tip is measured by the following method. A solution may be formed by adding a fluorescein sodium salt to a solvent, such that the concentration of the fluorescein sodium salt is 1 μg/ml. The solvent may be 70 vol. % ethanol and 30 vol. % cell culture grade water (70:30 EtOH/water). A 100 μL volume of the fluorescein solution is drawn into a 200 μL pipette tip. The solution is then dispensed from the pipette tip. The fluid remaining on the used tip surface is recovered in wash water by aspirating the used pipette tip with 100 μL of deionized water that is placed in one well of a 96-well plate and dispensing it back into the same well. This wash step (a rinse) is repeated two more times using the same 100 μL used wash water volume. The absorbance of the fluorescence of the resultant dispensed wash water is then measured in arbitrary fluorescence units (AFU) using a fluorescent plate reader set at 480 nm wavelength and the value is recorded as the rinse solution AFUs. The absorbance in AFU at 480 nm wavelength of the 1 μg/fluorescein solution, the 70% ethanol (EtOH) and 30% water solution (70:30 EtOH/water), and a 100% water solution are also measured. To remove any artifact of the 70:30 EtOH solvent on the 1 μg/fluorescein solution, the value of AFUs for the 70:30 EtOH solvent is subtracted from the value of AFUs for the 1 ug/fluorescein solution and the resultant value is recorded as the Aspirated AFUs. Likewise, to remove any artifact of the wash water itself on the rinse fluid, the value of the AFUs for the 100% water solution is subtracted from the value of the AFUs for the rinse solution and the resultant value is recorded as the Retained AFUs. The fluid retention of the pipette tip is calculated by dividing the Retained AFUs by the Aspirated AFUs, and then multiplying the resultant value by 100%.

The method for measuring the fluid retention of a pipette tip is used and described in detail in the Examples of the present disclosure. The pipette tip is washed by drawing 100 μL of deionized water into the pipette tip and dispensing the water from the pipette tip. It should be understood that the fluid retention of a pipette tip may be measured after any given aspirate/dispense cycle. For example, in the Examples of the present disclosure, the pipette tip is subjected to three aspirate/dispense cycles, with washing occurring in between each cycle. The fluid retention of a pipette tip may be measured after any one of the first, second, third, fourth, fifth, or any subsequent aspirate/dispense cycles. In some embodiments, a pipette tip may comprise a fluid retention of less than or equal to 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1% or even 0% after the first aspirate/dispense cycle.

The fluid retention of an article comprising the polymer composition may be greater than 7% less than a similar article lacking the alkyl silicone. As described herein, a “similar article lacking the alkyl silicone” refers to an article that is identical to the article comprising the polymer composition in both structure and composition, except that the alkyl silicone content of the polymer composition is replaced with the thermoplastic polymer in the “similar article lacking the alkyl silicone.” In some embodiments, the fluid retention of an article comprising the polymer composition described herein may be greater than 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or even 85% less than a similar article lacking the alkyl silicone. In some embodiments, the fluid retention of a pipette tip comprising the polymer composition described herein may be greater than 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or even 85% less than a similar pipette tip lacking the alkyl silicone after the first aspirate/dispense cycle.

Further, as described herein, the “amount of fluid retention” for a pipette tip is measured by the following method using gravimetric testing. A solution may be formed by adding 50 wt. % of glycerol, 40 wt. % McCormick® green food dye (or equivalent), and 10 wt. % deionized water. An article formed from a polymer composition is weighed for mass using a mass balance scale having at least three decimal places and the measurement is recorded (i.e., the pre-cycle mass). The pipette tip is added to a pipettor and then a single cycle of drawing up the described solution (aspirating) and then dispensing it is performed, referred to as an aspirate/dispense cycle. The pipette tip is then removed from the pipettor and re-weighed, and the measurement is recorded (i.e., the post-cycle mass). The pre-cycle mass is subtracted from the post-cycle mass and that difference in mass is the amount of fluid retained by the tip. Pipette tips formed from the polymer compositions described herein that have a gravimetric testing amount less than or equal to 6 mg per 200 μL of the described solution in a 200 μL pipette tip after a single aspirating dispensing cycle are considered to have a low amount of fluid retention.

In some embodiments, the amount of fluid retention in a 200 μL pipette tip formed from the polymer compositions described herein is less than or equal to 10.0 mg, 9.0 mg, 8.0 mg, 7.0 mg, 6.0 mg, 5.0 mg, 4.0 mg, 3.0 mg, 2.0 mg, 1.9 mg, 1.8 mg, 1.7 mg, 1.6 mg, 1.5 mg, 1.4 mg, 1.3 mg, 1.2 mg, 1.1 mg, 1.0 mg, 0.9 mg, 0.8 mg, 0.7 mg, 0.6 mg, 0.5, 0.4 mg, 0.3 mg, 0.2 mg, or 0.1 mg per 200 μL of a solution comprising 50 wt. % of glycerol, 40 wt. % McCormick® green food dye (or equivalent), and 10 wt. % deionized water, after a single aspirating dispensing cycle, as measured with gravimetric testing. In one specific embodiment, the amount of fluid retention in a 200 μL pipette tip formed from the polymer compositions described herein is less than or equal to 4 mg per 200 μL of a solution comprising 50 wt. % of glycerol, 40 wt. % McCormick® green food dye (or equivalent), and 10 wt. % deionized water, after a single aspirate/dispense cycle, as measured with gravimetric testing.

In addition to relatively low fluid retention, the articles comprising the polymer composition may have a relatively low bind. As used in the present disclosure “bind” refers to the retention of solutes on the surface of the article. For example, without limitation, some biological samples in solution, such as protein or DNA, may be retained on surfaces of various laboratory consumables, such as pipette tips. Even if the fluid retention of the pipette tip is low, such that little to no solvent is retained by the pipette tip, the solute, such as protein or DNA, may bind to the wall of the pipette tip and be retained if the pipette tip has a relatively high bind. Embodiments of articles comprising the polymer composition may have a low bind, which may reduce the retention of certain materials on the articles. Without intending to be bound by theory, reducing the surface charge or oxidation of an article may reduce interactions between the article and biomolecules. Staining agents, such as ethidium bromide for DNA or colloidal gold for proteins, may be used to demonstrate reduced biomolecule binding to the surface of articles comprising the polymer composition. Reduced biomolecule binding correlates to increase protein and DNA recovery.

In one or more embodiments, the article may comprise a protein recovery of greater than or equal to 63%. For example, the article may comprise a protein recovery greater than or equal to 63%, 65%, 67%, 69%, or even 71%. As described herein, “protein recovery” for a pipette tip is measured by the following method. 200 μL of a bovine serum albumin (BSA) sample (5 μg/ml) is drawn into a pipette tip. The BSA sample is held in the pipette tip for 10 minutes and then dispensed from the pipette tip and measured by a microBCA assay. “BCA” refers to bicinchoninic acid. The protein remaining in the BSA sample after being dispensed from the pipette tip relative to the protein concentration of the initial BSA sample, referred to as “protein recovery,” is then calculated.